It's all in the post-processing. Still, if the 5D saves you time, that's the camera for you!

I also don't send my (portrait) clients full rez images, at least not initially. Some Windows picture viewers open the image to full size immediately and it can be shocking to see the detail close up on a person's face if you're not expecting that. Try sending your clients proofs at 20% size. They'll never complain about too much detail.